The understanding of the molecular mechanisms involved in tissue-specific expression of salivary proteins is a central problem in molecular biology of the salivary gland. Alpha-amylase, a major secretory protein of the parotid gland, is often used as a model secretory protein gene for studies of the regulatory mechanisms. However, the molecular mechanisms involved in the regulation of amylase or any other secretory protein gene expression in salivary glands are not well understood. This is, in part, due to the unavailability of the salivary gland cell lines or transgenic systems that can be utilized to study the expression of secretory protein genes. The use of permanent culture cells that model tissue-specific expression of salivary gland genes in vivo would greatly facilitate studies to determine the regulatory mechanisms of the parotid amylase gene, as well as other secretory protein genes. We have recently obtained a tissue culture cell line (HSY) that originates from the human adenocarcinoma of the parotid gland. These cells secrete salivary gland type alpha-amylase. In addition, a glucose transporter which is expressed in parotid acinar cells is also detected in these cells. The objective of this proposal is to characterize the HSY cell line at the molecular level and to determine whether the cells can serve as a model cell line for studies of the transcriptional regulation in the parotid gland. The specific aims are: 1. To confirm the expression of the amylase and glucose transporter transcripts in HSY cells by identification of the respective gene transcripts. 2. To establish whether the cell line supports the expression of the amylase and/or glucose transporter genes when transfected with plasmid reporter gene constructs containing portions of the 5' flanking region of the respective gene. 3. To determine the most effective transfection method and reporter gene system for the expression studies using HSY cells.